Simplify the following expression: $p = \dfrac{1}{4k} - \dfrac{4}{3k}$
Solution: In order to subtract expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $4k$ and $3k$ $\lcm(4k, 3k) = 12k$ $ p = \dfrac{3}{3} \cdot \dfrac{1}{4k} - \dfrac{4}{4} \cdot \dfrac{4}{3k} $ $p = \dfrac{3}{12k} - \dfrac{16}{12k}$ $p = \dfrac{3 -16}{12k}$ $p = \dfrac{-13}{12k}$